"HSBC said its initial Chinese purchasing managers' index, or PMI, rose to a 13-month high of 50.4 in November from 49.5 last month. The reading ticked above the benchmark of 50, meaning that manufacturing is now in a state of accelerated expansion. The bank's final reading for the month will be released Dec. 1."
More: China's factories show accelerated growth - Nov. 21, 2012
Do the underlined words mean/ refer to performance?
They refer to the "Chinese purchasing managers' index, or PMI". Since the article states that the higher reading equates to a state of accelerated expansion, we may safely assume that they do equate to performance.
I'm not a teacher of English, but I have spoken it for (almost) all of my life....